1. Field of the Invention
The invention relates to radio equipment and more particularly to radio equipment which can ensure good transmission of radio waves even when the provision of a ground structure (ground) is difficult.
2. Prior Art
In order to efficiently radiate radio waves from an antenna connected to radio equipment, a circuit of the radio equipment or the body of the device has hitherto been grounded to the earth to provide electrical connection to the earth.
FIG. 1 is a schematic diagram showing the construction of a conventional radio transmitter. This radio transmitter 20 includes a signal wave generator 21 for generating a signal wave such as voice, an oscillator 22 for generating a high-frequency carrier, a modulator 23 for modulating the carrier by the signal wave according to a predetermined modulating method, an amplifier 24 for amplifying the modulated wave output from the modulator 23 to provide necessary electric power which is then supplied to an antenna 25, a power supply wire 26 for supplying electric power to each part, a power supply 27 for supplying electric power through the power supply wire 26, and a ground wire 29 for grounding a common ground 26A to the earth 28.
Regarding stable radiation of a modulated wave from the antenna 25, a common recognition in the art is that minimizing the grounding resistance derived from the ground wire 29 is preferred. When the grounding resistance can be minimized, reference potential high enough to operate the antenna 25 can be ensured and the drive of the antenna 25 can be accelerated to improve the radiation of the radio wave.
In the conventional radio equipment, however, when satisfactory grounding cannot be ensured, the reference potential becomes unstable and, consequently, the radiation of the radio wave is lowered. The lowered radiation results in lowered radio transmission efficiency, or otherwise the radio transmission becomes impossible. This tendency is significant particularly under such a condition that the transmission output is low.